However, the head of Scotland Yard standards said it was actually more practical to let some people quit.

Commander Peter Spindler, who heads the force's directorate of professional standards, also said complaints about Met officers had fallen by 9% in a year.This was the result of "a lot of hard work", he added.

'Slow' process

Mr Spindler said he hoped people understood that with more than 50,000 employees, there would be corruption in the force.

"We don't live in a perfect world," he said.

In many cases "it's actually more pragmatic to let them resign", Mr Spindler added.

In October, a PC who worked as an emergency phone operator was sacked for failing to respond to 141 "potentially dangerous" calls, while another officer indecently assaulted a "vulnerable" teenager.

Last month, two officers were dismissed for beating up three men after a car chase, and a trainee detective was sacked after sexually assaulting a vulnerable woman.

A centralised unit has been created in Earls Court, west London, to investigate staff suspected of wrongdoing.

But the disciplinary process was "slow" and officers awaiting hearings were "sitting there" at the taxpayers' expense in the meantime, said Det Ch Supt Richard Heselden, another anti-corruption detective.